Possible causes

Fuel pressure regulator.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1181 Description

The PCM receives fuel tank pressure (FTP) information from the natural gas (NG) module, which uses the information to infer the fuel rail pressure (FRP). The test fails when the inferred pressure is higher than a maximum calibrated value.

P1181 Information for specific makes

P1181 FORD
P1181 HYUNDAI